Abstract: A computer system includes a processor and a prefetch engine. The processor is configured to generate a demand access stream. The prefetch engine is configured to generate a first prefetch request and a second prefetch request based on the demand access stream, to output the first prefetch request to a first translation lookaside buffer (TLB), and to output the second prefetch request to a second TLB that is different from the first TLB. The processor performs a first TLB lookup in the first TLB based on one of the demand access stream or the first prefetch request, and performs a second TLB lookup in the second TLB based on the second prefetch request.

Abstract: A computer system includes a processor and a prefetch engine. The processor is configured to generate a demand access stream. The prefetch engine is configured to initiate a first prefetch request based on the demand access stream and perform a first prefetch that includes performing a translation lookaside buffer (TLB) lookup on a TLB structure in response to the first prefetch request. The processor determines a TLB entry in response to performing the TLB lookup and performs at least one second prefetch based on the TLB entry without performing a subsequent TLB lookup on the TLB structure.

Abstract: In at least one embodiment, a processing unit includes a processor core and a vertical cache hierarchy including at least a store-through upper-level cache and a store-in lower-level cache. The upper-level cache includes a data array and an effective address (EA) directory. The processor core includes an execution unit, an address translation unit, and a prefetch unit configured to initiate allocation of a directory entry in the EA directory for a store target EA without prefetching a cache line of data into the corresponding data entry in the data array. The processor core caches in the directory entry an EA-to-RA address translation information for the store target EA, such that a subsequent demand store access that hits in the directory entry can avoid a performance penalty associated with address translation by the translation unit.

Abstract: An information handling system, method, and processor that detects a store instruction for data in a processor where the store instruction is a reliable indicator of a future load for the data; in response to detecting the store instruction, sends a prefetch request to memory for an entire cache line containing the data referenced in the store instruction, and preferably only the single cache line containing the data; and receives, in response to the prefetch request, the entire cache line containing the data referenced in the store instruction.

Abstract: A computer system includes a processor and a prefetch engine. The processor is configured to generate a demand access stream. The prefetch engine is configured to initiate a first prefetch request based on the demand access stream and perform a first prefetch that includes performing a translation lookaside buffer (TLB) lookup on a TLB structure in response to the first prefetch request. The processor determines a TLB entry in response to performing the TLB lookup and performs at least one second prefetch based on the TLB entry without performing a subsequent TLB lookup on the TLB structure.

Abstract: A computer system includes a processor and a prefetch engine. The processor is configured to generate a demand access stream. The prefetch engine is configured to generate a first prefetch request and a second prefetch request based on the demand access stream, to output the first prefetch request to a first translation lookaside buffer (TLB), and to output the second prefetch request to a second TLB that is different from the first TLB. The processor performs a first TLB lookup in the first TLB based on one of the demand access stream or the first prefetch request, and performs a second TLB lookup in the second TLB based on the second prefetch request.

Abstract: Disclosed is a computer implemented method and system to dynamically adjust prefetch depth, the method comprising, identifying a first prefetch stream, wherein the first prefetch stream is identified in a prefetch request queue (PRQ), and wherein the first prefetch stream includes a first prefetch depth. The method also comprises determining a number of inflight prefetches, and comparing, a number of prefetch machines against the number of inflight prefetches, wherein each of the prefetch machines is configured to monitor one prefetch request. The method further includes adjusting, in response to the comparing, the first prefetch depth of the first prefetch stream.

Abstract: An information handling system, method, and processor that detects a store instruction for data in a processor where the store instruction is a reliable indicator of a future load for the data; in response to detecting the store instruction, sends a prefetch request to memory for an entire cache line containing the data referenced in the store instruction, and preferably only the single cache line containing the data; and receives, in response to the prefetch request, the entire cache line containing the data referenced in the store instruction.

Abstract: In at least one embodiment, a processing unit includes a processor core and a vertical cache hierarchy including at least a store-through upper-level cache and a store-in lower-level cache. The upper-level cache includes a data array and an effective address (EA) directory. The processor core includes an execution unit, an address translation unit, and a prefetch unit configured to initiate allocation of a directory entry in the EA directory for a store target EA without prefetching a cache line of data into the corresponding data entry in the data array. The processor core caches in the directory entry an EA-to-RA address translation information for the store target EA, such that a subsequent demand store access that hits in the directory entry can avoid a performance penalty associated with address translation by the translation unit.

Abstract: Disclosed is a computer implemented method to dynamically adjust prefetch depth, the method comprising sending, to a first prefetch machine, a first prefetch request configured to fetch a first data address from a first stream at a first depth to a lower level cache. The method also comprises sending, to a second prefetcher, a second prefetch request configured to fetch the first data address from the first stream at a second depth to a highest-level cache. The method further comprises determining the first data address is not in the lower level cache, determining, that the first prefetch request is in the first prefetch machine, and determining, in response to the first prefetch request being in the first prefetch machine, that the first stream is at steady state. The method comprises adjusting, in response to determining that the first stream is at steady state, the first depth.

Abstract: Operation of a multi-slice processor that includes a plurality of execution slices, a plurality of load/store slices, and one or more page walk caches, where operation includes: receiving, at a load/store slice, an instruction to be issued; determining, at the load/store slice, a process type indicating a source of the instruction to be a host process or a guest process; and determining, in accordance with an allocation policy and in dependence upon the process type, an allocation of an entry of the page walk cache, wherein the page walk cache comprises one or more entries for both host processes and guest processes.

Abstract: Operation of a multi-slice processor that includes a plurality of execution slices. Operation of such a multi-slice processor includes: determining, by a hypervisor, that consumption of memory controller resources, by a plurality of processing threads, is above a threshold quantity, wherein respective processing threads of the plurality of processing threads control respective prefetch settings; and responsive to determining that the consumption of the memory controller resources is above the threshold quantity, modifying individual memory controller usage of at least one of the plurality of processing threads such that the consumption of the memory controller resources is reduced below the threshold quantity.

Abstract: A computer system, processor, and method for processing information is disclosed that includes allocating a prefetch stream; providing a protection bubble to a plurality of cachelines for the allocated prefetch stream; accessing a cacheline; and preventing allocation of a different prefetch stream if the accessed cacheline is within the protection bubble. The system, processor and method in an aspect further includes providing a safety zone to a plurality of cachelines for the allocated prefetch stream, and advancing the prefetch stream if the accessed cacheline is one of the plurality of cachelines in the safety zone. In an embodiment, the number of cachelines within the safety zone is less than the number of cachelines in the protection bubble.

Abstract: A processor, system and/or techniques are disclosed for prefetching data streams in a processor. A prefetcher issues a plurality of requests to pre-fetch data from a stream in a plurality of streams; evaluates a confidence level of at least the first request based on an amount of confirmations observed in the stream; and assigns at least a first more aggressive prefetching ramping mode or a second less aggressive prefetching ramping mode based upon the confidence level of a thread associated with the prefetch request, wherein the prefetcher has one or more probationary states and is configured to transition between the first and second prefetching ramp mode by entering at least one of the probation states wherein the prefetcher continues to operate in the first prefetching ramp mode. In another aspect, the prefetcher may transition to the one or more probation states after a number of cycles.

Abstract: Verification of asynchronous page fault in a simulated environment. The methods include providing a simulated environment that includes a simulated processor core, a memory, and an interrupt handler. The methods also include executing a test code in the simulated environment by: executing a non-irritator thread code comprising a plurality of load instructions that span at least two slices of the simulated processor core, executing a first irritator thread code to bias against the execution of the plurality of load instruction by one of the at least two slices of the simulated processor core, and executing a second irritator thread code to invalidate caching of page table entries during execution of the plurality of load instructions in a fast access cache memory.

Abstract: Disclosed is a computer implemented method and system to dynamically adjust prefetch depth, the method comprising, identifying a first prefetch stream, wherein the first prefetch stream is identified in a prefetch request queue (PRQ), and wherein the first prefetch stream includes a first prefetch depth. The method also comprises determining a number of inflight prefetches, and comparing, a number of prefetch machines against the number of inflight prefetches, wherein each of the prefetch machines is configured to monitor one prefetch request. The method further includes adjusting, in response to the comparing, the first prefetch depth of the first prefetch stream.

Abstract: Disclosed is a computer implemented method to dynamically adjust prefetch depth, the method comprising sending, to a first prefetch machine, a first prefetch request configured to fetch a first data address from a first stream at a first depth to a lower level cache. The method also comprises sending, to a second prefetcher, a second prefetch request configured to fetch the first data address from the first stream at a second depth to a highest-level cache. The method further comprises determining the first data address is not in the lower level cache, determining, that the first prefetch request is in the first prefetch machine, and determining, in response to the first prefetch request being in the first prefetch machine, that the first stream is at steady state. The method comprises adjusting, in response to determining that the first stream is at steady state, the first depth.

Abstract: Verification of asynchronous page fault in a simulated environment. The methods include providing a simulated environment that includes a simulated processor core, a memory, and an interrupt handler. The methods also include executing a test code in the simulated environment by: executing a non-irritator thread code comprising a plurality of load instructions that span at least two slices of the simulated processor core, executing a first irritator thread code to bias against the execution of the plurality of load instruction by one of the at least two slices of the simulated processor core, and executing a second irritator thread code to invalidate caching of page table entries during execution of the plurality of load instructions in a fast access cache memory.

Abstract: A computer system for prefetching data in a multithreading environment includes a processor having a prefetching engine and a stride detector. The processor is configured to perform requesting data associated with a first thread of a plurality of threads, and prefetching requested data by the prefetching engine, where prefetching includes allocating a prefetch stream in response to an occurrence of a cache miss. The processor performs detecting each cache miss, and based on detecting the cache miss, monitoring the prefetching engine to detect subsequent cache misses and to detect one or more events related to allocations performed by the prefetching engine. The processor further performs, based on the stride detector detecting a selected number of events, directing the stride detector to switch from the first thread to a second thread by ignoring stride-1 allocations for the first thread and evaluating stride-1 allocations for potential strided accesses on the second thread.

Abstract: A processor, system and/or techniques are disclosed for prefetching data streams in a processor. A prefetcher issues a plurality of requests to pre-fetch data from a stream in a plurality of streams; evaluates a confidence level of at least the first request based on an amount of confirmations observed in the stream; and assigns at least a first more aggressive prefetching ramping mode or a second less aggressive prefetching ramping mode based upon the confidence level of a thread associated with the prefetch request, wherein the prefetcher has one or more probationary states and is configured to transition between the first and second prefetching ramp mode by entering at least one of the probation states wherein the prefetcher continues to operate in the first prefetching ramp mode. In another aspect, the prefetcher may transition to the one or more probation states after a number of cycles.